1. Field of the Invention
The present invention relates to a method and apparatus for treating an organic waste gas and, more particularly, to a method and apparatus for discharging an organic waste gas containing organic solvents etc. out of a system after a suitable oxidizing treatment.
2. Description of the Prior Art
Free discharge of waste gases containing noxious components such as organic solvents without any treatment such as oxidation causes air pollution. It has been, therefore, a common practice to effect a suitable treatment such as oxidation so as to render the gases harmless before such gases are discharged to the atmosphere.
A typical example of an apparatus for treating organic waste gases, designed to effect a suitable treatment before the gases are released to the atmosphere, will be explained with specific reference to FIG. 5 which is a sectional view of the apparatus. The treatment apparatus has a cylindrical casing 1 provided at its one end with an inlet 1a and at its other end with an outlet 1b, an activated carbon filter 2 disposed in the casing 1 such as to divide the space in the casing into two sections and adapted to adsorb any organic solvent carried by the waste gas, and a fan mounted in the casing 1 near the outlet 1b and adapted to induce the waste gas from a source (not shown) of the gas past the inlet 1a and to discharge the treated gas through the outlet 1b.
In operation, as the fan 3 operates, the waste gas (referred to as "organic solvent waste gas" hereinafter) containing air and a mist of suspended organic solvents such as methanol or trichlene is sucked from the source into the casing 1 through the inlet 1a as indicated by an arrow A. The organic solvent waste gas then flows through the activated carbon filter 2 so that the mist of the organic solvent is adsorbed by the activated carbon filter 2. The waste gas now free of the organic solvent is discharged to the outside of the system, i.e., into the atmosphere, through the outlet 1b of the casing 1 by the operation of the fan 3.
The activated carbon filter 2 adsorbs the organic solvent to its full capacity, so that it can be used for a considerably long time. However, since the capacity of the activated carbon filter 2 is limited, adsorption power progressively decreases and, hence, renewal or regeneration of the filter becomes necessary when the amount of the solvent trapped by the filter has materially reached full capacity.
Thus, the known method of treating an organic solvent waste gas requires the renewal or regeneration of the activated carbon filter 2 when its adsorption power has been reduced. The renewal of the activated carbon filter 2 is laborious and requires the whole system to be stopped during the renewal operation, resulting in reduced efficiency in treating the waste gas. On the other hand, the renewal of this type of filter 2 is generally conducted by steaming the filter 2 so as to allow the organic solvent on the filter 2 to be released into the steam, and then discharging the steam containing the solvent to the outside of the system. Obviously, discharge of the steam containing an organic solvent directly to the atmosphere causes air pollution. Thus, the regeneration of the activated carbon filter 2 essentially requires a suitable treatment of the steam containing the organic solvent.